June 30, 2008 �?The caffeine that many of us rely on to get us going in the mornings or perk us up during the day could hold the key to unlocking the mysteries of multiple sclerosis.

When consumed in large amounts in a newly reported study, caffeine was found to protect against multiple sclerosis by blocking key steps in the development of the disease.

But the study involved mice, and its authors say it is not yet clear if the findings apply to humans.

If they do, the research could one day lead to new ways to prevent and treat MS and other autoimmune diseases, like rheumatoid arthritis and lupus, they say.

About 400,000 Americans and 2.5 million people worldwide have multiple sclerosis.

"This is really exciting because the results were completely unexpected," Linda Thompson, PhD, of Oklahoma Medical Research Foundation, tells WebMD.

Caffeine Protected Mice

The study involved mice genetically engineered by Thompson to develop an MS-like disease called encephalomyelitis (EAE).

Mice in the study did not develop the disease, however, when fed large amounts of caffeine �?equivalent to six to eight cups of caffeinated coffee a day.

The caffeine blocked a compound called adenosine that triggers the events that lead to the mouse form of MS.

"For MS to develop, immune cells must cross the blood-brain barrier," the study's principal author Margaret Bynoe, PhD, of Cornell University, tells WebMD. "Caffeine blocked the adenosine receptor, preventing these immune cells from getting through."

Specifically, caffeine prevented cells from the immune system from entering the brain and damaging the protective coating that surrounds the nerve cells known as myelin.

This destruction of myelin over time causes the progressive symptoms characteristic of multiple sclerosis, which can range from muscle tingling to complete paralysis and can also include mild to severe impairment in speech, vision, and mental function.

Although the researchers focused on caffeine, other adenosine blockers may prove to be more useful in future studies, Bynoe says.

More Coffee? Not So Fast

The study appears in the July 8 issue of the journal Proceedings of the National Academy of Sciences. It was also presented in April at the 95th Annual Meeting of the American Association of Immunologists in San Diego.

"When the report first came out, people called and asked me if they should drink more coffee," Bynoe says. "But that is really missing the point. It remains to be seen if caffeine is protective in humans."

Studies that could answer this question are currently under way in Bynoe's lab.